Letter abstract
Nature Geoscience 1, 385 - 389 (2008)
Published online: 25 May 2008 | doi:10.1038/ngeo206
Subject Category: Volcanology, mineralogy and petrology
Coupled caldera subsidence and stirring inferred from analogue models
Ben M. Kennedy1, A. Mark Jellinek1 & John Stix2
Caldera-forming eruptions can be explosive and lead to the eruption of phenomenal volumes of magma that can devastate the global environment1. Such eruptions involve ground subsidence related to catastrophic sinking of a magma chamber roof, accompanied by buoyant flow of magma through a ring conduit around the sinking roof 2. Previous work points to a feedback between subsidence and eruption: eruption initiates subsidence of the chamber roof, which in turn drives the ongoing eruption3. Although subsidence-driven eruption dominates caldera evolution4, the coupled dynamics of subsidence and magma flow are poorly understood. Here, we use analogue models to show that, under most conditions, caldera subsidence is spatially and temporally variable, leading to complicated and vigorous magma stirring and mixing. On the basis of the experimental results and a scaling analysis, we construct a regime diagram that helps demonstrate how the coupled flow and subsidence are influenced by the fluid dynamics and geometry of the system. The vigorous stirring we infer can considerably modify the style of subsidence and can explain textural, petrological and geochemical variation in deposits that have been related to caldera-forming eruptions.
- Earth and Ocean Sciences, University of British Columbia, 6339 Stores Road Vancouver, BC V6T 1Z4, Canada
- Earth and Planetary Sciences, McGill University, 3450 University Street, Montreal, Quebec, H3A 2A7, Canada
Correspondence to: Ben M. Kennedy1 e-mail: Bkennedy@eos.ubc.ca
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